"They belong to the perch family," said the Doctor, "and so does the 'golo,' or _Lates niloticus_. There are several varieties of perch in Africa, but these are the most abundant." During their rest under the tents, while the sun was high in the sky, the conversation naturally turned upon the African lakes and the people living around them. Fred asked about the people that inhabit the islands of other lakes, and also about some tribes that dwell in houses standing in the water. [Illustration: LAKE MOHRYA, WITH VILLAGES.] "I can only refer you to Cameron," said the Doctor, in reply. "He visited a small lake, in his journey across Africa, where the people actually live in the water. There are few lakes where this would be possible, on account of the presence of crocodiles, who would drive to the land everybody they did not eat. The lake seen by Cameron was called Mohrya, and lies east of Tanganyika, on the route to the Atlantic Ocean. It is rather a pond than a lake, as it is only a couple of miles long by one in width, and lies in a basin surrounded by low hills. "Cameron tried to obtain boats to take him to these curious dwellings, but could not do so, as the people on land had none, and the lake-dwellers were very shy of allowing strangers to visit their houses. All he could do was to sit on the shore and study them with his telescope. [Illustration: A HOUSE IN THE WATER.] "The huts were built on poles driven into the bed of the lake, and the floor of each hut was about six feet above the surface of the water. Boats were kept under the huts, and nets were stretched between the poles, so that they could be dried by the sun and air. The people live entirely in these huts, and only come to land to cultivate their gardens, which lie near the water. "They go from house to house," the Doctor continued, "by the simple process of swimming. It is rumored that there are large snakes in the water, whose bites are poisonous; but Mr. Cameron could see nothing of them, and evidently the story is untrue, or the people would be more careful. They keep fowls and goats in their huts, and bring the former to land to graze, but they always return home with them when night comes on." Fred wished to know something of this curious tribe, but the Doctor was unable to give him farther information. He added, however, that lake dwellings are of very ancient origin, and are mentioned in history by Herodotus and other Greek writers. "Yes," replied Fred, "I have read of them in descriptions of Switzerland and Ireland, and we saw huts in the water when we were in Siam and Java." [Illustration: IDEAL REPRESENTATION OF A SWISS LAKE-VILLAGE.]